Because substance use in adolescence is a social event, we propose the Duke-Carolina Trans-Disciplinary Prevention Research Center to address the pervasive influence of peers on adolescent drug-use behavior. Emergent findings suggest that youth proliferate drug-use attitudes and behavior in contexts with deviant peers and that these deviant influences play a major role in adolescent drug use. In spite of these findings, however, government interventions often aggregate deviant peers without adequate supervision to avoid deviant peer contagion (e.g., alternative schools, training schools, special classrooms, boot camps), and prevention curricula do not sufficiently take into account the pervasiveness of peer influences. The proposed Center will be co-led by Kenneth Dodge, a NIDA-supported Senior Scientist Award recipient and developmental psychopathologist, and Philip Costanzo, a leading social psychologist of peer influences. The Center will bring together scholars at Duke University and the University of North Carolina at Chapel Hilt from the disciplines of economics, psychology, sociology, neuropharmacology, public policy, statistics, psychiatric epidemiology, and health behavior in order to form trans-disciplinary working groups that will complete programs of research. The 34 members will conduct basic science studies and will translate that knowledge into novel preventive interventions at each of three levels of peer influence, which will constitute Programs of Research: 1) cognitive and emotional processes that operate intrapersonally but are influenced by peers; 2) the social psychology of interpersonal peer interaction in dyads and small groups; and 3) institutional peer effects at a macro-level. Each of these Programs will be supported by three Cores, for Administration, Data, and Practice. The Administrative Core will nurture an intellectual climate through leadership, seminars, postdoctoral training, and budget management. The Data Core will help researchers locate their research in community, school, and policy settings; process data in a centralized data center; and provide expert statistical consultation in quantitative methods of analyzing change. The Practice Core will bring practitioners and policy makers into ongoing interaction with researchers to translate basic science into novel prevention programs for implementation and evaluation. The Center will be governed by an Executive Committee of the Directors of the three Programs of Research and the three Cores. External Scientific and Practice Advisory Boards will provide essential guidance. The Center will be evaluated annually for implementation and impact through logs of activities, surveys of members, compilation of published products, and external reviews.